HOME

TheInfoList



OR:

Wound licking is an instinctive response in humans and many other animals to cover an injury with saliva.
Dog The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the wolf. Also called the domestic dog, it is derived from the extinct Pleistocene wolf, and the modern wolf is the dog's nearest living relative. Do ...
s,
cat The cat (''Felis catus'') is a domestic species of small carnivorous mammal. It is the only domesticated species in the family Felidae and is commonly referred to as the domestic cat or house cat to distinguish it from the wild members of ...
s, small
rodent Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia (), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are n ...
s,
horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million yea ...
s, and
primate Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians ( monkeys and apes, the latter including ...
s all lick wounds. Saliva contains tissue factor which promotes the blood clotting mechanism. The enzyme
lysozyme Lysozyme (EC 3.2.1.17, muramidase, ''N''-acetylmuramide glycanhydrolase; systematic name peptidoglycan ''N''-acetylmuramoylhydrolase) is an antimicrobial enzyme produced by animals that forms part of the innate immune system. It is a glycoside ...
is found in many tissues and is known to attack the cell walls of many gram-positive bacteria, aiding in defense against infection. Tears are also beneficial to wounds due to the lysozyme enzyme. However, there are also infection risks due to bacteria in the mouth.


Mechanism

Oral mucosa The oral mucosa is the mucous membrane lining the inside of the mouth. It comprises stratified squamous epithelium, termed "oral epithelium", and an underlying connective tissue termed '' lamina propria''. The oral cavity has sometimes been des ...
heals faster than
skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different de ...
, suggesting that saliva may have properties that aid wound healing. Saliva contains cell-derived tissue factor, and many compounds that are
antibacterial An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention ...
or promote healing. Salivary tissue factor, associated with
microvesicles Microvesicles (ectosomes, or microparticles) are a type of extracellular vesicle (EV) that are released from the cell membrane. In multicellular organisms, microvesicles and other EVs are found both in tissues (in the interstitial space between c ...
shed from cells in the mouth, promotes wound healing through the extrinsic blood coagulation cascade. The enzymes
lysozyme Lysozyme (EC 3.2.1.17, muramidase, ''N''-acetylmuramide glycanhydrolase; systematic name peptidoglycan ''N''-acetylmuramoylhydrolase) is an antimicrobial enzyme produced by animals that forms part of the innate immune system. It is a glycoside ...
and
peroxidase Peroxidases or peroxide reductases ( EC numberbr>1.11.1.x are a large group of enzymes which play a role in various biological processes. They are named after the fact that they commonly break up peroxides. Functionality Peroxidases typically ca ...
, defensins,
cystatin The cystatins are a family of cysteine protease inhibitors which share a sequence homology and a common tertiary structure of an alpha helix lying on top of an anti-parallel beta sheet. The family is subdivided as described below. Cystatins sho ...
s and an
antibody An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...
, IgA, are all antibacterial.
Thrombospondin Thrombospondins (TSPs) are a family of secreted glycoproteins with antiangiogenic functions. Due to their dynamic role within the extracellular matrix they are considered matricellular proteins. The first member of the family, thrombospondin 1 (TH ...
and some other components are
antiviral Antiviral drugs are a class of medication used for treating viral infections. Most antivirals target specific viruses, while a broad-spectrum antiviral is effective against a wide range of viruses. Unlike most antibiotics, antiviral drugs do no ...
. A protease inhibitor, secretory leukocyte protease inhibitor, is present in saliva and is both antibacterial and antiviral, and a promoter of wound healing. Nitrates that are naturally found in saliva break down into nitric oxide on contact with
skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different de ...
, which will inhibit
bacterial growth 250px, Growth is shown as ''L'' = log(numbers) where numbers is the number of colony forming units per ml, versus ''T'' (time.) Bacterial growth is proliferation of bacterium into two daughter cells, in a process called binary fission. Providing ...
. Saliva contains
growth factors A growth factor is a naturally occurring substance capable of stimulating cell proliferation, wound healing, and occasionally cellular differentiation. Usually it is a secreted protein or a steroid hormone. Growth factors are important for reg ...
such as epidermal growth factor,
VEGF Vascular endothelial growth factor (VEGF, ), originally known as vascular permeability factor (VPF), is a signal protein produced by many cells that stimulates the formation of blood vessels. To be specific, VEGF is a sub-family of growth factors ...
, TGF-β1, leptin, IGF-I,
lysophosphatidic acid Lysophosphatidic acid (LPA) is a phospholipid derivative that can act as a signaling molecule. Function LPA acts as a potent mitogen due to its activation of three high-affinity G-protein-coupled receptors called LPAR1, LPAR2, and LPAR3 (a ...
, hyaluronan and NGF, which all promote healing, although levels of EGF and NGF in humans are much lower than those in rats. In humans, histatins may play a larger role. As well as being growth factors, IGF-I and TGF-α induce antimicrobial peptides. Saliva also contains an analgesic, opiorphin. Licking will also tend to
debride Debridement is the medical removal of dead, damaged, or infected tissue to improve the healing potential of the remaining healthy tissue. Removal may be surgical, mechanical, chemical, autolytic (self-digestion), and by maggot therapy. In po ...
the wound and remove gross contamination from the affected area. In a recent study, scientists have confirmed through several experiments that the protein responsible for healing properties in human saliva is, in fact, histatin. Scientists are now looking for ways to make use of this information in ways that can lead to chronic wounds, burns, and injuries being healed by saliva.


In animals

It has been long observed that the licking of their wounds by dogs might be beneficial. Indeed, a dog's saliva is bactericidal against the bacteria ''
Escherichia coli ''Escherichia coli'' (),Wells, J. C. (2000) Longman Pronunciation Dictionary. Harlow ngland Pearson Education Ltd. also known as ''E. coli'' (), is a Gram-negative, facultative anaerobic, rod-shaped, coliform bacterium of the genus '' Esc ...
'' and '' Streptococcus canis'', although not against coagulase-positive '' Staphylococcus'' or ''
Pseudomonas aeruginosa ''Pseudomonas aeruginosa'' is a common encapsulated, gram-negative, aerobic–facultatively anaerobic, rod-shaped bacterium that can cause disease in plants and animals, including humans. A species of considerable medical importance, ''P. aerug ...
''. Wound licking is also important in other animals. Removal of the salivary glands of mice and rats slows wound healing, and communal licking of wounds among rodents accelerates wound healing. Communal licking is common in several primate species. In
macaques The macaques () constitute a genus (''Macaca'') of gregarious Old World monkeys of the subfamily Cercopithecinae. The 23 species of macaques inhabit ranges throughout Asia, North Africa, and (in one instance) Gibraltar. Macaques are principal ...
, hair surrounding a wound and any dirt is removed, and the wound is licked, healing without infection.


Risks

Wound licking is beneficial but too much licking can be harmful. An
Elizabethan collar An Elizabethan collar, E collar or pet cone (sometimes humorously called a treat funnel, pet lamp-shade, pet radar dish, dog-saver, or cone of shame) is a protective medical device worn by an animal, usually a cat or dog. Shaped like a truncate ...
may be used on pet animals to prevent them from biting an injury or excessively licking it, which can cause a
lick granuloma A lick granuloma, also known as acral lick dermatitis, is a skin disorder found most commonly in dogs, but also in cats. In dogs, it results typically from the dog's urge to lick the lower portion of one of their legs. The lesion can initially be ...
. These lesions are often infected by pathogenic bacteria such as ''Staphylococcus intermedius''. Horses that lick wounds may become infected by a stomach
parasite Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...
, '' Habronema'', a type of nematode worm. The
rabies Rabies is a viral disease that causes encephalitis in humans and other mammals. Early symptoms can include fever and tingling at the site of exposure. These symptoms are followed by one or more of the following symptoms: nausea, vomiting, ...
virus may be transmitted between animals, such as the kudu antelopes by wound licking of wounds with residual infectious saliva.


In humans


Religion and legend

There are many legends involving healing wounds by licking them or applying saliva. Saint
Magdalena de Pazzi Mary Magdalene de' Pazzi, OCarm ( it, Maria Maddalena de' Pazzi; April 2, 1566 – May 25, 1607), was an Italian Carmelite nun and mystic. She has been declared a saint by the Catholic Church. Life De' Pazzi was born at Florence, Italy, on ...
is said to have cured a nun of sores and scabs in 1589 by licking her limbs. The Roman Emperor
Vespasian Vespasian (; la, Vespasianus ; 17 November AD 9 – 23/24 June 79) was a Roman emperor who reigned from AD 69 to 79. The fourth and last emperor who reigned in the Year of the Four Emperors, he founded the Flavian dynasty that ruled the Empi ...
is said to have performed a healing of a blind man using his saliva.
Pliny the Elder Gaius Plinius Secundus (AD 23/2479), called Pliny the Elder (), was a Roman author, naturalist and natural philosopher, and naval and army commander of the early Roman Empire, and a friend of the emperor Vespasian. He wrote the encyclopedic ' ...
in his '' Natural History'' reported that a fasting woman's saliva is an effective cure for bloodshot eyes. In the
Hebrew Bible The Hebrew Bible or Tanakh (;"Tanach"
'' Gospel Gospel originally meant the Christian message (" the gospel"), but in the 2nd century it came to be used also for the books in which the message was set out. In this sense a gospel can be defined as a loose-knit, episodic narrative of the words a ...
s, there are three different incidents in which
Jesus Jesus, likely from he, יֵשׁוּעַ, translit=Yēšūaʿ, label= Hebrew/ Aramaic ( AD 30 or 33), also referred to as Jesus Christ or Jesus of Nazareth (among other names and titles), was a first-century Jewish preacher and religiou ...
uses saliva to cure (, , ). Köstenberger suggests "by using saliva to cure a man, Jesus claims to possess unusual spiritual authority."


Risks

There are potential health hazards in wound licking due to infection risk, especially in
immunocompromised Immunodeficiency, also known as immunocompromisation, is a state in which the immune system's ability to fight infectious diseases and cancer is compromised or entirely absent. Most cases are acquired ("secondary") due to extrinsic factors that a ...
patients. Human saliva contains a wide variety of bacteria that are harmless in the mouth, but that may cause significant infection if introduced into a wound. A notable case was a
diabetic Diabetes, also known as diabetes mellitus, is a group of metabolic disorders characterized by a high blood sugar level ( hyperglycemia) over a prolonged period of time. Symptoms often include frequent urination, increased thirst and increased ...
man who licked his bleeding thumb following a minor bicycle accident, and subsequently had to have the thumb amputated after it became infected with '' Eikenella corrodens'' from his saliva.


Licking of people's wounds by animals


History and legend

Dog saliva has been said by many cultures to have curative powers in people. "''Langue de chien, langue de médecin''" is a French
saying A saying is any concisely written or spoken expression that is especially memorable because of its meaning or style. Sayings are categorized as follows: * Aphorism: a general, observational truth; "a pithy expression of wisdom or truth". ** Adag ...
meaning "''A dog's tongue is a doctor's tongue''", and a Latin quote that ''"Lingua canis dum lingit vulnus curat"'' or ''"A dog's saliva can heal your wound"'' appears in a thirteenth-century manuscript. In
Ancient Greece Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean Sea, Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of Classical Antiquity, classical antiquity ( AD 600), th ...
, dogs at the
shrine A shrine ( la, scrinium "case or chest for books or papers"; Old French: ''escrin'' "box or case") is a sacred or holy space dedicated to a specific deity, ancestor, hero, martyr, saint, daemon, or similar figure of respect, wherein they ...
of Aesculapius were trained to lick patients, and snake saliva was also applied to wounds.
Saint Roch Roch (lived c. 1348 – 15/16 August 1376/79 (traditionally c. 1295 – 16 August 1327, also called Rock in English, is a Catholic saint, a confessor whose death is commemorated on 16 August and 9 September in Italy; he is especially invoked a ...
in the
Middle Ages In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire ...
was said to have been cured of a plague of sores by licking from his dog. The
Assyria Assyria ( Neo-Assyrian cuneiform: , romanized: ''māt Aššur''; syc, ܐܬܘܪ, ʾāthor) was a major ancient Mesopotamian civilization which existed as a city-state at times controlling regional territories in the indigenous lands of the ...
n Queen
Semiramis ''Samīrāmīs'', hy, Շամիրամ ''Šamiram'') was the semi-legendary Lydian- Babylonian wife of Onnes and Ninus, who succeeded the latter to the throne of Assyria, according to Movses Khorenatsi. Legends narrated by Diodorus Siculus, who dr ...
is supposed to have attempted to resurrect the slain
Armenia Armenia (), , group=pron officially the Republic of Armenia,, is a landlocked country in the Armenian Highlands of Western Asia.The UNbr>classification of world regions places Armenia in Western Asia; the CIA World Factbook , , and ' ...
n king
Ara the Beautiful Ara the Handsome ( hy, Արա Գեղեցիկ ''Ara Gełec‘ik'') is a semi-legendary Armenian hero and king. Ara is notable in Armenian literature for the popular legend in which he was so handsome that the Assyrian queen Semiramis waged war agai ...
by having the
dog The dog (''Canis familiaris'' or ''Canis lupus familiaris'') is a domesticated descendant of the wolf. Also called the domestic dog, it is derived from the extinct Pleistocene wolf, and the modern wolf is the dog's nearest living relative. Do ...
god Aralez lick his wounds. In the
Scottish Highlands The Highlands ( sco, the Hielands; gd, a’ Ghàidhealtachd , 'the place of the Gaels') is a historical region of Scotland. Culturally, the Highlands and the Lowlands diverged from the Late Middle Ages into the modern period, when Lowland S ...
in the nineteenth century, dog saliva was believed to be effective for treating wounds and sores. In the
Gospel of Luke The Gospel of Luke), or simply Luke (which is also its most common form of abbreviation). tells of the origins, birth, ministry, death, resurrection, and ascension of Jesus Christ. Together with the Acts of the Apostles, it makes up a two-vol ...
(16:19-31), Lazarus the Beggar's sores are licked by dogs, although no curative effects are reported by the Evangelist.


Modern cases

There are contemporary reports of the healing properties of dog saliva. Fijian fishermen are reported to allow dogs to lick their wounds to promote healing, and a case of dog saliva promoting wound healing was reported in the '' Lancet'' medical journal.


Risks

As with the licking of wounds by people, wound licking by animals carries a risk of infection. Allowing pet cats to lick open wounds can cause
cellulitis Cellulitis is usually a bacterial infection involving the inner layers of the skin. It specifically affects the dermis and subcutaneous fat. Signs and symptoms include an area of redness which increases in size over a few days. The borders of ...
and
sepsis Sepsis, formerly known as septicemia (septicaemia in British English) or blood poisoning, is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. This initial stage is follo ...
due to bacterial infections. Licking of open wounds by dogs could transmit
rabies Rabies is a viral disease that causes encephalitis in humans and other mammals. Early symptoms can include fever and tingling at the site of exposure. These symptoms are followed by one or more of the following symptoms: nausea, vomiting, ...
if the dog is infected with rabies, although this is said by the
CDC The Centers for Disease Control and Prevention (CDC) is the national public health agency of the United States. It is a United States federal agency, under the Department of Health and Human Services, and is headquartered in Atlanta, Georgi ...
to be rare. Dog saliva has been reported to complicate the healing of
ulcers An ulcer is a discontinuity or break in a bodily membrane that impedes normal function of the affected organ. According to Robbins's pathology, "ulcer is the breach of the continuity of skin, epithelium or mucous membrane caused by sloughing o ...
. Another issue is the possibility of an
allergy Allergies, also known as allergic diseases, refer a number of conditions caused by the hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic derm ...
to
protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
s in the saliva of pets, such as
Fel d 1 Fel d 1 is a secretoglobin protein complex that, in cats, is encoded by the ''CH1'' (chain 1/Fel d 1-A) and ''CH2'' (chain 2/Fel d 1-B) genes. Among cats, Fel d 1 is produced largely in their saliva and by the sebaceous glands located in the ...
in cat allergy and Can f 1 in dog allergy. Cases of serious infection following the licking of wounds by pets include: * Dog ** A diabetic man who was infected by ''
Pasteurella __NOTOC__ ''Pasteurella'' is a genus of Gram-negative, facultatively anaerobic bacteria. ''Pasteurella'' species are nonmotile and pleomorphic, and often exhibit bipolar staining ("safety pin" appearance). Most species are catalase- and oxidase ...
dagmatis'' due to the licking of his injured toe by his dog, causing a spinal infection. ** A woman recovering from knee surgery suffered a persistent infection of the knee with ''Pasteurella'' after her dog licked a small wound on her toe. ** A dog lick to an Australian woman's minor burn caused
sepsis Sepsis, formerly known as septicemia (septicaemia in British English) or blood poisoning, is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. This initial stage is follo ...
and necrosis due to ''
Capnocytophaga canimorsus ''Capnocytophaga canimorsus'' is a fastidious, slow-growing, Gram-negative rod of the genus '' Capnocytophaga''.Pers C, Gahrn-Hansen B, and Frederiksen W. 1996. ''Capnocytophaga canimorsus'' Septicemia in Denmark, 1982-1995: Review of 39 Cases. ...
'' infection, resulting in the loss of all her toes, fingers and a leg. ** ''C. canimorsus'' caused acute
kidney failure Kidney failure, also known as end-stage kidney disease, is a medical condition in which the kidneys can no longer adequately filter waste products from the blood, functioning at less than 15% of normal levels. Kidney failure is classified as eit ...
due to sepsis in a man whose open hand wound was licked by his dog. ** A 68-year-old man died from sepsis and
necrotizing fasciitis Necrotizing fasciitis (NF), also known as flesh-eating disease, is a bacterial infection that results in the death of parts of the body's soft tissue. It is a severe disease of sudden onset that spreads rapidly. Symptoms usually include red or p ...
after a wound was licked by his dog. ** A patient with a
perforated eardrum A perforated eardrum (tympanic membrane perforation) is a hole in the eardrum. It can be caused by infection (otitis media), trauma, overpressure (loud noise), inappropriate ear clearing, and changes in middle ear pressure. An otoscope can be us ...
developed meningitis after his dog passed on a ''Pasteurella multocida'' infection by licking his ear. * Cat ** A woman recovering from surgery for endometrial cancer suffered from ''Pasteurella multocida'' infection causing an abscess after her cat licked the incision. ** A
blood donor A blood donation occurs when a person voluntarily has blood drawn and used for transfusions and/or made into biopharmaceutical medications by a process called fractionation (separation of whole blood components). Donation may be of whole bloo ...
whose cat licked her chapped fingers passed on ''Pasteurella'' infection to a 74-year-old transfusion recipient. ** A seven-week-old boy contracted meningitis due to ''Pasteurella'' from contact with pet saliva.


Idiomatic use

To "lick your wounds" means to "withdraw temporarily while recovering from a defeat" The phrase was spoken by Antony in
John Dryden '' John Dryden (; – ) was an English poet, literary critic, translator, and playwright who in 1668 was appointed England's first Poet Laureate. He is seen as dominating the literary life of Restoration England to such a point that the per ...
's seventeenth century play '' All for Love'':


See also

*
Cat scratch fever ''Cat Scratch Fever'' is the third studio album by American rock musician Ted Nugent. It was released on May 13, 1977, by Epic Records. Vocalist Derek St. Holmes, who had left the band during the recording of the album ''Free-for-All'', had com ...
*
Folklore Folklore is shared by a particular group of people; it encompasses the traditions common to that culture, subculture or group. This includes oral traditions such as tales, legends, proverbs and jokes. They include material culture, ranging ...
*
Maggot therapy Maggot therapy (also known as larval therapy) is a type of biotherapy involving the introduction of live, disinfected maggots (fly larvae) into non-healing skin and soft-tissue wounds of a human or other animal for the purpose of cleaning out th ...
*
Personal grooming Grooming (also called preening) is the art and practice of cleaning and maintaining parts of the body. It is a species-typical behavior. In animals Individual animals regularly clean themselves and put their fur, feathers or other skin cov ...
* Skin repair * Vampire bat feeding *
Zoonosis A zoonosis (; plural zoonoses) or zoonotic disease is an infectious disease of humans caused by a pathogen (an infectious agent, such as a bacterium, virus, parasite or prion) that has jumped from a non-human (usually a vertebrate) to a human. ...


References

{{DEFAULTSORT:Wound Licking Injuries Ethology Hygiene Infectious diseases Saliva